A bra is an undergarment that covers, supports and elevates breasts. Bras may also be worn to improve the perceived shape and size of the breasts, to restrain breast movement during exercise, for prosthetic purposes, or to facilitate nursing.
Typically, bras comprise a cup for each breast, a center panel (or gore), a band running around the torso under the breasts, side and back panels, hook and eye sets, and shoulder straps. The cups may be supported by underwires made of metal and sometimes coated in plastic. Underwire is often used in strapless bras to support the breasts. Wirefree bras support breasts using strengthened, larger cups and wider bands. These bras are sometimes referred to as softcup bras. Bras are usually fastened with a hook fastener on the band, typically at the back. A fastener may also be located in the front of a bra, between the cups. Bras may also be pulled on over a woman's head and have no fasteners. Bras may contain padding to improve comfort, conceal the nipples, or enhance bust size. Materials used often include a fabric such as cotton, polyester, Spandex or lace.
Many women find it difficult to locate a well-fitting and comfortable bra. Reasons why locating a well-fitting bra may be difficult include a wide variation in manufacturers' sizes, and a wide variation in the shape of women's bodies. An accurate bra fit is determined by correctly calculating the chest size (or band size) and breast volume (the cup size). The band size is typically adjusted using the two or three alternate sets of fastening hooks and eyes in the clasp. A set of two bra straps, typically over the shoulders, can usually also be adjusted slightly.
Wearing a bra which does not fit correctly may lead to a number of problems, including back pain, restricted breathing, abrasions, breast pain and poor posture. Back pain, neck pain and shoulder pain may be caused by a bra which causes the shoulders to support the majority of the weight of the chest. Typical designs may also constrict chest movement during breathing. In large-breasted women, wearing an improperly-fitted bra may result in maceration (loss of skin), chafing, intertrigo (rash), and fungal infections. Some women experience mastodynia or mastalgia (breast pain), particularly when performing strenuous physical activity or exercise. A properly fitted bra reduces such pain. Very large breasts can reduce the normal curve of the upper and mid-back region and may eventually lead to severe low back pain and poor posture.